Abstract: A highly dependable method for the detection of in vivo induction of chromosomal aberration has been developed in liver,bone-marrow and spermatogonial cells in mice subjected to partial hepatectomy.The inductivities of chromosomal aberrations by benzene and cyclophosphamide are different.When the partially hepatectomized mice were injected intraparitoneally with freshly prepared cyclophosphamide solution (15 μg/g body wt.),the inductivity to the three target cells is bone-marrow cells>regenerating liver cells>spermatogonial cells,whereas the inductivity of benzene (0.01 ml/mouse,2 subcutaneous injections) is regenerating liver cells>bone-marrow cells>spermatogonial cells.To develop this procedure will facilitate the detection of drug-induced clastogenic activity,particularly those requiring tissue-specific metabolic activated procarcinogens/promutagens and in vivo comparison of clastogenic sensitivity among the three types of tissues.